A tire conventionally has a generally torroidal shape and includes two lateral parts forming sidewalls joined by a crown part forming a tread.
The thickness of the tire generally varies according to the part concerned. For example, in the case of a tire intended to be fitted to a roadwork type vehicle, the crown part forming the tread may have a thickness of 30 cm while the lateral parts forming the sidewalls each have a thickness of approximately 2 to 3 cm.
It is known to fabricate a tire by heating a blank tire in a mould of annular general shape around an axis of revolution. Heating the blank tire causes its vulcanization. As the tread is thicker than each of the sidewalls, it is necessary to distribute the heat appropriately in the mould in order to transfer more calories into the tread than into a sidewall. It is known to master this heat distribution by evacuating excess calories in the parts of the mould in contact with the sidewalls. The excess calories are evacuated by means of a cooling heat-transfer liquid circulating in the parts of the mould in contact with the sidewalls, more particularly in an annular passage of the mould extending around the axis of the mould. The passage includes a liquid admission inlet and a liquid discharge outlet situated angularly in the vicinity of the admission inlet so that the liquid travels a substantially complete turn in the passage.
Because it exchanges heat with the mould, the temperature of the heat-transfer liquid increases along its circular path in the passage with the result that the cooling of the mould by the heat-transfer liquid is less effective at the end of the travel of the liquid in the passage than at the beginning. There is therefore a relatively large temperature difference of the heat-transfer liquid between the liquid inlet and the liquid outlet of the passage.
It is possible to reduce the temperature difference between the liquid entry into the passage and the liquid outlet from the passage by increasing the flow rate at which the liquid is admitted. This limits the duration of the heat transfer between the mould and the liquid as the liquid circulates and thus reduces the temperature difference of the liquid between the inlet and the outlet.
However, this solution is not entirely satisfactory.